1. Magnetic Fields

2. What is a cow magnet?

3. Magnetic Field Lines
Defined as the direction N pole of a compass points in the field.
Drawn from N to S

4. Lab Magnetic Fields
Mapping magnetic fields using the compass method

5. Lab Magnetic Fields
Use iron fillings poured over a piece of paper to visualize magnetic field of each magnet

6. Magnetic Flux Number of field lines in any region
Greatest around the poles of a magnet

7. Fact or Fiction?
If a very strong magnet is brought near the corner of a dollar bill, the bill will be attracted.

8. What is the advantage of using a horseshoe magnet?
Poles are close together.

10. Which material affects a magnetic field?
Index cards
Razor blade
Stream of water
Straight pin
Aluminum foil
Only ____________ substances can distort a magnetic field.

11. Metal detectors
Smart phones now have a built in magnetometer to detect magnets in addition to the Earth’s Magnetic Field.

12. How does an automatic traffic signal know that your car is there?
The coil of wire is in the street and when your car passes over it, that tells the signal to turn green.

13. Earth’s Magnetic Field
Earth has a magnetic field shaped similar to a big bar magnet.
Center of Earth is much too hot for domains to stay aligned.
Earth’s polarity can switch as well, which it has done so more than 170 times. (Last reversal 700,000 years ago)

14. Aurora Borealis
Northern Lights

15. Aurora Borealis
High temperatures on the sun’s surface produce _____________, the fourth phase of matter consisting of charged particles. These charged particles travel throughout the solar system as _________ __________. When charged particles reach the region of the earth’s outer atmosphere called the ________________, their motion is controlled by the earth’s magnetic field.
plasma
solar
wind
magnetosphere

16. Aurora Borealis
The charged particles are able to slip through the earth’s magnetic field at the ___________ and enter the atmosphere. They collide with ______________ in atoms of gases like oxygen and nitrogen and transfer _________, making the electrons jump to higher energy levels. When they fall, they give off visible __________ of different colors.
poles
electrons
energy
light

17. Southern Lights
Aurora austrailis

18. Show what you know Magnetic field lines are drawn
a) from north to south c) from positive to negative
b) from south to north d) from negative to positive
2) This diagram represents the magnetic field between
a) two N poles
b) two S poles
c) N pole (left) and S pole (rt)
d) S pole (left) and N pole (rt)

19. 3) Magnetic flux is
a) the number of magnetic field lines in an area
b) an indication of the strength of a magnetic field
c) greatest at the poles of a magnet
d) all of these
4) The cause of the earth’s magnetic field is
a) a giant bar magnet imbedded in the center of the earth
b) the aligned domains in the iron rich solid core
c) still unknown
5) The Aurora Borealis
a) originates on the sun as solar wind
b) is caused by charged particles transferring energy to the
atoms of gases in the atmosphere
c) can only be seen at northern latitudes